In a study published in the U.S. journal Cell Reports, researchers found that blocking a specific protein in white fat triggered the fat to begin to brown into beige fat, a type of fat in between white and brown, thus causing the fat cells to heat up and burn calories.

"Our goal is to find a way to treat or prevent obesity," said first author Irfan Lodhi, an assistant professor of medicine at the Washington University School of Medicine in St. Louis.

"Our research suggests that by targeting a protein in white fat, we can convert bad fat into a type of fat that fights obesity," Lodhi said.

Beige fat was discovered in adult humans in 2015. Though it is almost like an intermediary between white fat and brown fat, it functions more like brown fat and can protect against obesity, said Lodhi.

His team conducted a series of experiments in mice, creating a genetic strain of animals that didn't make a key protein in their white fat cells.

Those mice had more beige fat and were leaner than their littermates, even when they ate the same amount of food as other mice. They also burned more calories.

"Mice normally have very low levels of the protein, called PexRAP, in their brown fat," he said.

"When we put the mice into a cold environment, levels of the protein also decreased in white fat, allowing that fat to behave more like brown fat. Cold induces brown and beige fats to burn stored energy and produce heat," he added.

Lodhi said if the PexRAP protein could be blocked safely in white fat cells in humans, people might have an easier time losing weight.

"The challenge will be finding safe ways to do that without causing a person to overheat or develop a fever, but drug developers now have a good target," he said.